I really want to replace O2 sensors but at the same time be sure that I have found the culprit as parts are expensive. Just one thing though on Sat the code switch to lean on bank 2 (p0174) and STFT was perfect on bank 1 and bank 2 was +20 what gives? and then Sun. and today back to lean on both banks.

2nd question, by any chance, have you ever unplugged your MAF and looked at O2 voltages on scanner? do they stay the same or there is a difference? I am asking this because when I unplug MAF my O2's are around .7 - .9 running rich on both banks. But if I plug in MAF O2 voltages drop to .03 - .05 not even the normal lean which is .1 volts.